HP-35 for sale - but which version do I have?

[Jeff O.]

(04-23-2014 06:04 PM)chancewest Wrote:  * Power supply plug is circular and has two pins - that's why I haven't been able to turn it on and test yet.

If you have a power supply with a round plug and two pins, it is not for the HP-35. The HP-35 power supply plug is rectangular, and has three pins, matching the recess on the back of the calculator.

If you want to test it, take the battery compartment cover off and apply 4.5 Volts DC to the two prongs in there, according to the polarity indicated below:

(04-24-2014 08:53 PM)chancewest Wrote:  Is a version 3 good?

It looks to be in good cosmetic condition, and if it works it is definitely "good". As far as value, version 1 (red-dot) units command the highest value, probably five to ten times the value of other versions. Version 2 units with the bugs may be next highest in value, I guess kind of like the desire for misprinted stamps or coins that got into circulation. Version 2 without bugs might also be valued, since they were obviously returned to HP and "repaired" to eliminate the bugs, demonstrating HP's commitment to quality above all else. Version 4 may be next, since they have the redesigned keyboard and represent the last of the line. So maybe version 3 is least collectible, but certainly desirable as either a single example of such a fine machine, or to fill out a collection.

The above are solely my impressions, nothing more. If you want maximum value, find a way to test to see if it works, then put on eBay. Or watch a few ebay auctions, decide on what you feel is a fair price, and sell to a collector here. Note that many sellers at ebay put them up with ridiculously high buy-it-now prices, hoping to hook a neophyte collector who does not know real value. So only count completed auctions in your assessment of value.